A small two-cycle internal combustion engine used a driving source for portable working machines such as a chain saw, a brush cutter and the like is equipped with a diaphragm type carburetor so that excellent operation of the internal combustion engine may be controlled in any attitude.
As disclosed in Japanese Patent Application Laid-Open Publication No. 41955/1987, there is proposed an arrangement wherein when the engine is started, fuel is supplied from a fuel tank to a metering chamber by a manual primer pump, the fuel being also directed to an accumulator chamber, and a button for an accumulator is operated simultaneously with the starting rotation (cranking) operation of the engine to supply the fuel in the accumulator from a fuel nozzle to an air intake passage of a carburetor. However, recently, the internal combustion engine equipped with a battery operated motor has been mounted on the aforementioned portable working machine. It is desirable that an electric power supply for driving the electric motor is also utilized to automatically perform a series of operations.
It is an object of the present invention to provide an apparatus for supplying start-fuel to the internal combustion engine for a portable type working machine in which replenishing of fuel to a metering chamber and supplying of start-fuel to a fuel nozzle are automatically accomplished by an electric primer pump.